Giant hogweed found in Gig Harbor

Giant hogweed has been identified in Gig Harbor and special precautions must be taken to remove as contact with the plant’s sap can cause blisters and permanent scarring.(Photo: Pierce County Noxious Weed Control Board courtesy photo)

Giant hogweed is a very large, invasive plant that’s listed as a Class A noxious weed on the Pierce County, state and federal noxious weed registers.

It’s also listed as a public health hazard because its clear, watery sap is toxic and can cause painful, burning blisters that can develop into purple or blackened scars, especially if affected skin is exposed to sunlight within 48 hours. If the sap enters the eye, it can cause temporary or even permanent blindness, according to the Pierce County Noxious Weed Control Board.

It was originally imported from Asia as an ornamental plant, but has spread to parks, woods, roadsides and back yards across the state — including Gig Harbor, where it was recently found in a yard on Soundview Drive.

Giant hogweed is a member of the carrot family, but, unlike the healthy vegetables grown in vegetable gardens, giant hogweed can grow up to 20 feet tall and has large, wide leaves that can be more than three feet across.

The stems are hollow and covered with dark reddish-purple splotches and coarse white hairs. “We call those purple splotches ‘nature’s warning system,’” Morgan Heileson, biologist and education specialist from the NWCB, said in a phone interview. “Those splotches are the most telling characteristic that identifies giant hogweed.”

Mature plants have large, wide umbels of white flowers that develop seeds. Like other seed-bearing plants, giant hogweed seeds can be carried by birds and animals and even by the wind, which is why it’s important to remove the flowers before they go to seed.

Jim Towslee, field inspector for the NWCB confirmed that the Soundview Drive plant was giant hogweed and notified the property owners to cut off the flowers right away and get rid of the plant. He’ll also do a follow-up inspection to make sure the plant is gone.

If a person suspects they’ve found a giant hogweed plant, they can either self-identify it or contact NWCB for positive ID, Heileson said.

“If you find giant hogweed and are trying to get rid of it, it’s very important to wear long sleeves, long pants and even goggles. You have to avoid contact with the sap, which is in every part of the plant. And it can squirt up to five feet when the stem is cut or broken.”

The entire plant must be removed — including the roots.

“Once you have it all cut down and dug up, put it in a big black garbage bag and put it in the garbage,” she said. “Don’t put it in the yard waste.”

If a patch of hogweed is found — for example in a vacant lot or meadow — it’s important to call NWCB right away. “We’ll locate the property owner and we can provide a list of contractors we work with who can get rid of it,” Heileson said.

Giant hogweed plants have also been found on the Key Peninsula.

The Washington State Invasive Species Council notes that giant hogweed is sometimes confused with cow parsnip, but grows much taller and wider. In fact, it grows so big and so densely that it can crowd out native species and completely take over large areas, making the soil vulnerable to erosion.

The plant is on the Washington Plant Quarantine list, meaning that it’s illegal to transport, buy, sell or distribute plants, plant parts or seeds.

Pierce County lists giant hogweed as one of the “Terrible 10” plants. Because it’s a Class A Noxious Weed, eradication is mandatory and will be enforced, according to the board’s website. The goal is to completely eradicate Class A weeds like giant hogweed and prevent them from becoming established.

For information, visit the Pierce County Weed Control board at piercecountyweedboard.org or call 253-798-7263.